WO2018214631A1 - 一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法 - Google Patents

一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法 Download PDF

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WO2018214631A1
WO2018214631A1 PCT/CN2018/080114 CN2018080114W WO2018214631A1 WO 2018214631 A1 WO2018214631 A1 WO 2018214631A1 CN 2018080114 W CN2018080114 W CN 2018080114W WO 2018214631 A1 WO2018214631 A1 WO 2018214631A1
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alloy
die
nano
casting
phase
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French (fr)
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赵玉涛
怯喜周
陈刚
陈飞
殷来大
殷敏
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江苏大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/002—Castings of light metals
    • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
    • B22D21/04—Casting aluminium or magnesium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/07—Metallic powder characterised by particles having a nanoscale microstructure
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0408—Light metal alloys
    • C22C1/0416—Aluminium-based alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1036—Alloys containing non-metals starting from a melt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1036—Alloys containing non-metals starting from a melt
    • C22C1/1047—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites
    • C22C1/1052—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites by mixing and casting metal matrix composites with reaction
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1036—Alloys containing non-metals starting from a melt
    • C22C1/1068—Making hard metals based on borides, carbides, nitrides, oxides or silicides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1036—Alloys containing non-metals starting from a melt
    • C22C1/1073—Infiltration or casting under mechanical pressure, e.g. squeeze casting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
    • C22C32/0073—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only borides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the invention relates to an aluminum-based composite material, in particular to a high-strength anti-fatigue in-situ nano-reinforced aluminum alloy for a shock absorption component of an automobile engine and a high-density die-casting method thereof.
  • shock absorber components such as shock absorbing brackets and shock absorbing shells
  • aluminum alloy components among which AlSi9Cu3 aluminum alloy die castings are widely used. It is a complex power system safety device for shock absorbers, shock absorbing shells and oil pump casings of automobile engines.
  • the AlSi9Cu3 alloy itself has low strength and fatigue resistance (tensile strength 260 MPa, yield strength 140 MPa, elongation 1%; load ⁇ 7.6 kN, bench fatigue times 500,000 times);
  • the parts produced by the conventional die-casting process have more pores (internal cavities in the anatomical plane: number ⁇ 1 / cm 2 , pore diameter ⁇ 0.5 mm), and cannot be effectively heat-treated and toughened (solid solution + aging, or high temperature aging)
  • the precipitation phase of the casting usually has a coarse needle-like or sheet-like structure, which becomes a technical bottleneck for improving the performance of the aluminum die casting. Therefore, the AlSi9Cu3 die castings have problems such as deformation, fracture and seal failure during the severe service process, which affects the operation of the engine and causes major safety hazards.
  • particle reinforced aluminum matrix composites with light weight and low production cost in automotive parts has become a new trend, but the addition of particle reinforcement has weak bonding and poor toughness of the interface between the particles and the substrate; in situ generation of particle reinforced aluminum alloys in recent years It has become a hot spot, especially the in-situ nano-particle-reinforced aluminum alloy has the characteristics of good toughness and strong anti-fatigue ability. It is an ideal lightweight material, and the uniformity of the distribution of nanoparticles in the matrix is the key to its performance.
  • the present invention proposes an in-situ nanoparticle reinforcement of an AlSi9Cu3 aluminum alloy for a shock absorption component of an automobile engine, and develops a progressive high-density die-casting technique, which allows the nanoparticle to be uniformly distributed in the matrix by means of rapid solidification crystallization of the die-casting part, and fully utilizes the nano-reinforcing body.
  • the strengthening effect of the progressive high-density die-casting technology avoids the problem that the traditional abrupt die-casting rate causes a large number of pores in the casting and cannot be effectively heat-treated, and the mechanical properties of the die-casting part are remarkably improved.
  • the application number is CN201611179327.5, the Chinese invention patent for the rolling process of a microalloyed aluminum-based composite material, and the in-situ particle reinforced AlSi9Cu3 alloy and the remaining hot direct rolling process are disclosed.
  • the invention discloses a high performance in situ nanoparticle reinforced AlSi9Cu3 alloy and its progressive high density die casting technology.
  • the application number is CN200610118386.1, the Chinese invention patent of the extrusion casting method named aluminum alloy automobile engine bracket.
  • the published engine bracket production technology is extrusion casting, and the alloy used is not AlSi9Cu3 die-cast aluminum alloy.
  • the application number is CN201611213315.X, which is a Chinese invention patent for the production process of a shock absorber support.
  • French invention with the application number FR2969176A1 entitled Manufacturing part egcylinical casing of motor vehicle, complising molding aluminum-silicon-copper alloy in mold, removing molded part, placing molded part in heat treatment furnace, and quenching molded part at a given temperature
  • the patent discloses a process for producing AlSi9Cu3 automobile parts by a conventional casting method, and the present invention solves the problem of low plasticity and low fatigue resistance of the AlSi9Cu3 shock absorbing member produced by the high-efficiency die-casting process.
  • DE102008039976A1 entitled Heat-treated hot isostatic pressing of light-metal cast components, complies treating a body made of light metal cast alloys such as aluminum cast alloys and magnesium cast alloys, discloses the use of hot isostatic Pressure to improve the performance of light alloy parts such as AlSi9Cu3, and the technology of this patent is to obtain high-density high-performance AlSi9Cu3 engine shock absorbing parts by progressive die casting.
  • the object of the present invention is to reduce the strong plasticity and fatigue resistance of the AlSi9Cu3 die-casting aluminum alloy for the shock absorber components of the existing automobile engine, and in particular, it cannot meet the shortage of high-strength, anti-fatigue and anti-shock technology requirements of high-performance engine components.
  • alloy composition control and in-situ nano-hardening combined with nonlinear high-pressure die casting, in-situ nano-ceramic reinforcement reinforcement in the intragranular and grain boundaries is achieved while increasing the content, rounding and refining of the alloy precipitation phase.
  • the shock absorbing bracket and the shell of the automobile engine produced by the invention can have a tensile strength of 352 MPa, a yield strength of 285 MPa and an elongation of 10.6%.
  • the final product is tested for durability through a dedicated gantry, with a minimum number of cycles of 1 million cycles, which is much higher than the 500,000 times required by the customer, reaching the German Volkswagen (damping bracket) DIN EN1706-1998 standard and Japan Mazda (damping) Housing) MES MM 621-ADC12 standard, but also exceeds the low-efficiency low-cost casting (low-pressure casting + solid solution + aging heat treatment) production of shock-absorbing bracket performance (tensile strength 300MPa, yield strength) 210MPa, elongation 7.5%).
  • the invention relates to a high-strength anti-fatigue in-situ nano-reinforced aluminum alloy for vibration damping components of an automobile engine and a high-density die-casting method thereof, which are obtained by alloy composition control and in-situ nano-hardening, and combined with optimized nonlinear high-pressure die casting to obtain intragranular and crystal
  • the boundary contains a large number of uniformly dispersed nano-ZrB 2 ceramic reinforcements, which contain nano-Al 3 Er precipitates, including eutectic Si phase, Mg 2 Si phase, Al 2 Cu phase and alloy phase containing Fe phase. , rounded die castings.
  • the preparation method of the invention comprises the following steps:
  • Alloy melting The AlSi9Cu3 alloy was melted to 750-780 ° C and held for 10 min.
  • the AlSi9Cu3 alloy is a commercial alloy, and the specific chemical composition has an element mass percentage of Si 8.0 to 11.0, Cu 2.0 to 3.5, Zn 1.0 to 1.5, Mg 0.3 to 0.5, Fe ⁇ 0.8, and Mn 0.1 to 0.5.
  • step (3) Introducing Er and Ni elements, adjusting the content of Fe and Mn elements in the alloy and refining the degassing: adding the Al-Er, Al-Fe and Al-Mn intermediate alloys and pure Ni to the composite melting obtained in step (2) In the body, and using graphite stirring rotor agitation to promote the alloy to fully mix, the holding time is 10-15min; then the powdery composite refining agent with particle size less than 500 ⁇ m is blown into the melt through the hollow channel of the graphite rotor with inert gas, The melt is refined and degassed to remove the slag generated in the high-temperature melting and reaction of the alloy and the hydrogen dissolved in the melt.
  • the refining temperature is 730-750 ° C, and the refining holding time is 25-30 min.
  • the content of bismuth nickel iron in the step (3) alloy is Er: 0.1-0.15, Fe: 1.0-1.5, Mn: 0.5-1.0, and Ni 0.5-1.0.
  • the melt obtained in step (3) is cooled to 660-700 ° C and kept warm, and then pure Mg and pure Zn are pressed into the melt after refining and degassing by using a bell jar. Start the graphite stirring rotor and stir slowly, keep the stirring time >15min, so that Mg, Zn dissolves into the alloy and avoids the inhalation of the melt, and the content of magnesium and zinc in the alloy of step (4) reaches Mg: 0.5-1.0. Zn: 1.5 to 2.5.
  • Nonlinear high pressure die casting the composite melt obtained in step (4) is placed in the thermal insulation package of the die casting machine, and the nanocomposite reinforced die casting is obtained by die casting using an optimized nonlinear die casting process, wherein the injection speed is from small to small Large parabolic injection, to achieve a slow filling 2.5-3m / s in the early stage, the end of the instantaneous high-speed filling of the nonlinear filling (maximum injection speed of 40-50m / s, die casting pressure of 100-150MPa).
  • the aging treatment (natural aging or artificial aging) obtained by the step (5) is performed to obtain a high-strength anti-fatigue and good damping property in-situ nano-reinforced aluminum alloy die-casting.
  • the Al-Zr, Al-B, Al-Er, Al-Fe and Al-Mn intermediate alloys are preferably intermediate alloys having a high alloying element content, such as Al-10Zr, Al-10B, Al-20Er, Al- 20Fe and Al-10Mn.
  • the in-situ synthesis of the nano ZrB 2 ceramic reinforcement refers to the thermodynamic-kinetic property of using ZrB 2 in the multi-alloy system with low Gibbs free energy and Zr having low solubility and low thermal diffusion coefficient in Al.
  • nano-sized ZrB 2 ceramic particles are synthesized in situ in a size of 20-80 nm, the content is 2-6 wt.% of the alloy mass, and the synthesis temperature is 840-860 °C.
  • the in-situ nano ZrB 2 ceramic particles can be used as a heterogeneous nucleation core to improve the nucleation rate of the alloy, refine the grains, and finally contain the dispersion inside the alloy grains, which is significantly improved.
  • the strength and fatigue resistance of the alloy on the other hand, the nano-ZrB 2 ceramic particles which are not the core of nucleation will be dispersed in the grain boundary during the process of grain growth, which can effectively pin the grain boundary and hinder the migration of the grain boundary. While improving the strength of the alloy, the interface damping effect is maximized to improve the damping performance of the alloy.
  • the introduction of Er and Ni elements, adjusting the content of Fe and Mn elements in the alloy and refining degassing refers to the introduction of 0.1-0.15 wt.% of Er in the alloy, and on the other hand, the low solubility in the aluminum solution by means of Er. (0.1wt.%), the Al 3 Er heterogeneous nucleation core is precipitated in the alloy melt to increase the nucleation rate of aluminum, refine the alloy grains, and on the other hand, the Er element in the alloy is dissolved in the alloy.
  • the L1 2 type nano Al 3 Er precipitated phase which is finely and lattice-matched with the aluminum matrix is well precipitated, which significantly improves the ageing strength and fatigue resistance of the alloy die casting;
  • the purpose of increasing the Fe element content in the alloy is to improve
  • the content of Fe precipitated in the alloy increases the strength of the alloy, further improves the anti-sticking properties of the alloy, avoids the increase of the precipitated phase content of the alloy, the difficulty of demolding and the problem of sticking due to the decrease of the expansion system, and the introduction of Ni element and the enhancement of Mn element.
  • the purpose of the content is to convert Fe-like ⁇ -Fe phase in Ni, Mn and alloy into block or Chinese-shaped ⁇ -Al(Mn,Fe)Si and ⁇ -Al(Ni,Fe)Si phases, avoiding Fe
  • the increase in the content produces a large amount of acicular ⁇ -Fe phase which reduces the plastic toughness of the alloy.
  • the content of the Mg and Zn elements is adjusted to further increase the content of the precipitated phase in the alloy to improve the strength and fatigue resistance of the alloy, and to improve the damping property of the alloy by increasing the phase boundary.
  • the non-linear high-pressure die-casting process refers to a new type of die-casting machine that is programmable by the die-casting cylinder speed, and combines the optimized high-pressure die-casting process to avoid turbulence and volume during the melt filling process.
  • the gas facilitates the discharge of gas in the cavity and promotes the infiltration and dispersion of the nano-reinforcing body under the instantaneous high-speed high pressure filled with the cavity to obtain a die-cast product with less tissue defects and excellent performance.
  • the injection speed is from small to large parabolic injection, to achieve a slow filling 2.5-3m / s in the early stage, the end of the instant high-speed filling of the nonlinear filling (maximum injection speed of 40-50m / s, die casting pressure Up to 100-150 MPa).
  • the high-temperature aging heat treatment is advantageous for the low porosity of the progressive die-casting part, and the aging heat treatment temperature of the workpiece can be improved to promote the effective precipitation of the strengthening phase and the circular passivation of the silicon phase, the high-temperature aging heat treatment temperature.
  • the range is from 200 ° C to 350 ° C.
  • Fig. 1(a) is a metallographic structure diagram of a conventional AlSi9Cu3 die-casting part
  • (b) is a metallurgical structure diagram of a high-strength anti-fatigue and damping property of the in-situ nano-reinforced aluminum alloy shock-absorbing bracket die-casting part prepared by the present invention, from two gold It can be seen from the phase diagram that the needle-like precipitates in the die-casting parts prepared by the patented technology disappear, and are transformed into a granular or short-shaped rounded precipitate phase, which improves the dispersion degree of the precipitated phase and is beneficial to the workpiece's strong plasticity and fatigue. Improved performance.
  • FIG. 2 is a TEM structure diagram of a high-strength anti-fatigue and good damping property of an in-situ nano-reinforced aluminum alloy shock-absorbing bracket die-casting part prepared by the present invention. It can be seen from the figure that the intra-crystal and crystal of the die-casting part prepared by the patent are used.
  • the in-situ nano ZrB 2 ceramic reinforcing phase and the finer Al 3 Er uniform nanoprecipitate phase exist in the boundary, which is beneficial to the comprehensive improvement of the workpiece's strong plasticity, fatigue resistance and damping performance.
  • the optimized nonlinear high pressure die casting technology is used to prepare the automobile engine. Shock bracket.
  • the molten 500Kg commercial AlSi9Cu3 alloy (760 ° C) was transferred into the intermediate holding furnace, then the Al-10Zr and Al-10B intermediate alloys were added to the holding furnace and heated to 850 ° C, while the graphite stir rotor was used to stir the melt to promote the alloy. Fully mixed, holding time is 15min, then the alloy is cooled to 750 ° C and kept warm; Al-20Er, Al-20Fe and Al-10Mn and pure Ni are added to the melt, and the powder with particle size less than 500 ⁇ m is stirred for 15 minutes.
  • the compound refining agent is blown into the melt through the hollow passage of the graphite rotor with an inert gas, and the melt is refined and degassed to remove the slag generated in the high-temperature melting and reaction of the alloy and the hydrogen dissolved in the melt, and refining.
  • the time is 30 min, the temperature is maintained at 750 ° C, the temperature is lowered to 680 ° C after the end of refining degassing, and the pure Mg and pure Zn are pressed into the melt after refining and degassing with a bell jar, the graphite stirring rotor is started, and the stirring is slow.
  • the incubation time was 18 min, and the final composition of the alloy was Si 9.5, Cu 3 , Zr 3.5, B 0.75, Zn 1.5, Mg 0.8, Fe 1.3, Mn 1.0, Ni 0.7, Er 0.12, and the balance was Al.
  • the linear high-pressure die-casting process prepares the shock-absorbing bracket, in which the early stage is 3m/s slow filling, in order to realize the advection filling and facilitate the smooth discharge of gas in the mold cavity. When the cavity is full (the riser is not full), the pressure is increased. The shooting speed is up to 40m/s, and the pressure is maintained to 100MPa, and the dwell time is 15s.
  • the die-cast damping bracket is obtained.
  • the die-cast blank of the pouring riser and the flash edge is removed and placed in a heat treatment furnace for artificial aging, the aging temperature is 300 ° C, and the aging time is 8 hours.
  • the needle-like precipitate phase in the die casting prepared in this patent disappears compared with the conventional AlSi9Cu3 die casting. It is transformed into a granular or short piece of rounded precipitated phase, which improves the dispersion degree of the precipitated phase, which is beneficial to the improvement of the workpiece's strong plasticity and fatigue performance.
  • 2 is a TEM structure diagram of a die-casting die-casting part prepared by the process of the present embodiment. It can be seen from the figure that a large number of in-situ nano-ZrB 2 ceramic reinforcing phases exist in the intragranular and grain boundaries of the die-casting parts prepared by the patent. And the finer uniform nano-Al 3 Er nano-precipitation phase is beneficial to the comprehensive improvement of the workpiece's strong plasticity, fatigue resistance and damping performance.
  • the optimized nonlinear high pressure die casting technology is used to prepare the automobile engine. Shock shell (complex structure is difficult to fill and discharge gas is difficult, usually reduce Mg content, increase die casting pressure, improve die casting performance and yield).
  • the molten 500Kg commercial AlSi9Cu3 alloy (750 ° C) was transferred into the intermediate holding furnace, then the Al-10Zr and Al-5B intermediate alloys were added to the holding furnace and heated to 840 ° C, while the graphite stir rotor was used to stir the melt to promote the alloy. Fully mixed, holding time is 10min, then the alloy is cooled to 740 ° C and kept warm; Al-10Er, Al-10Fe and Al-10Mn and pure Ni are added to the melt, and the powder with particle size less than 500 ⁇ m is stirred for 10 minutes.
  • the compound refining agent is blown into the melt through the hollow passage of the graphite rotor with an inert gas, and the melt is refined and degassed to remove the slag generated in the high-temperature melting and reaction of the alloy and the hydrogen dissolved in the melt, and refining.
  • the time is 25 min, the temperature is maintained at 740 ° C, the temperature is lowered to 660 ° C after the end of refining degassing, and pure Mg and pure Zn are pressed into the melt after refining and degassing with a bell jar, the graphite stirring rotor is started, and the stirring is slow.
  • Insulation stirring time 20min so that the final composition of the alloy reaches Si 11, Cu 3.5, Zr 5.0, B 1.0, Zn 2.0, Mg 0.5, Fe 1.5, Mn 1.0, Ni 0.5, Er 0.15, the balance is Al, and finally the composite will be obtained.
  • the linear high-pressure die-casting process prepares the shock-absorbing shell, in which the early stage is 5m/s slow filling, in order to realize the advection filling and facilitate the smooth discharge of gas in the mold cavity, and the cavity is filled (the riser is not full), and the time is increased.
  • the injection speed was increased to 50 m/s, and the pressure was maintained at 150 MPa for 15 s to obtain a die-cast damping housing.
  • the die-cast blank from which the riser and the flash are cut off is placed in a heat treatment furnace for artificial aging, the aging temperature is 250 ° C, and the aging time is 10 hours.
  • the molten 500Kg commercial AlSi9Cu3 alloy (780 ° C) was transferred into the intermediate holding furnace, then the Al-10Zr and Al-5B intermediate alloys were added to the holding furnace and heated to 860 ° C, while the graphite stir rotor was used to stir the melt to promote the alloy.
  • the temperature is maintained at 750 ° C, after the end of refining, the temperature is lowered to 680 ° C and pure Mg and pure Zn are pressed into the melt after refining and degassing with a bell jar, the graphite stirring rotor is started, and the stirring is slow, the stirring time is kept.
  • the final composition of the alloy is Si 11, Cu 2.5, Zr 5.0, B 1.0, Zn 2.5, Mg 1.0, Fe 1.5, Mn 1.0, Ni 1.0, Er 0.1, the balance is Al, and finally the composite melt obtained will be Optimized nonlinear high pressure die casting
  • the art preparation oil pump casing in which the early stage is 4m/s slow filling, to achieve the advection filling and facilitate the smooth discharge of gas in the mold cavity, and to increase the injection speed until the cavity is full (the feeder is not full) 50m/s, and maintaining the pressure to 130MPa, the time is 15s, to obtain the die-cast oil pump casing.
  • the die-casting blank of the pouring riser and the flashing edge is removed and placed in a heat treatment furnace for artificial aging, the aging temperature is 220 ° C, and the aging time is 15 hours.
  • the AlSi9Cu3 alloy was used as raw material to prepare the shock absorber for automobile engine by using the optimized nonlinear high pressure die casting technology.
  • the molten 500Kg commercial AlSi9Cu3 alloy (700 °C) was prepared by using the optimized nonlinear high-pressure die-casting technology to prepare the shock absorber for automobile engine, and the artificial casting effect of the die-casting blank for cutting the riser and the flash was performed.
  • the aging temperature was 300 °C, and the aging was performed. The time is 8 hours.
  • Al-10Zr, Al-10B, Al-20Er, Al-20Fe, Al-10Mn intermediate alloy and pure Ni, pure Mg, pure Zn, and AlSi9Cu3 were used as raw materials to prepare shock absorbers for automobile engines by conventional die-casting technology.
  • the die casting was subjected to aging treatment by the same aging process as in Example 1.

Abstract

一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法。通过原位纳米强化和合金成分调控，并结合优化的非线性高压压铸工艺获得压铸件。借助原位纳米ZrB 2增强体和纳米Al 3Er析出相的尺度效应、界面效应、异质形核效应，显著提高合金的强度、抗疲劳性能和阻尼性能；与此同时，提高了Mg、Zn和Fe元素含量，并引入Mn和Ni元素，在提高强化相含量、获得高强度的同时，使Al-Fe相等有害的粗大析出相有效细化和圆顿化，并保障合金良好的压铸性能。

Description

一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法 技术领域
本发明涉及铝基复合材料，特指一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法。
背景技术
随着汽车轻量化的发展，传统上采用高强钢的汽车发动机减震部件(如：减震支架、减震壳体)，也逐渐被铝合金构件替代，其中AlSi9Cu3铝合金压铸件被广泛地用作汽车发动机的减震支架、减震壳体、油泵壳体等结构复杂的动力系统安全件。然而，一方面，AlSi9Cu3合金本身的强塑性和抗疲劳性能偏低(抗拉强度260MPa，屈服强度140MPa，延伸率1％；载荷±7.6kN，台架疲劳次数为50万次)；另一方面，常规压铸工艺生产的零部件气孔较多(解剖面内部空穴：数目≤1个/cm 2，孔径≤0.5mm)，无法进行有效的热处理强韧化(固溶+时效，或高温时效)，导致铸件的析出相通常呈粗大针状或片状结构，成为提高铝制压铸件性能的技术瓶颈。从而，使AlSi9Cu3压铸件在苛刻的服役过程中出现变形、断裂和密封失效等问题，影响发动机的运行、产生重大安全隐患。
质量轻、生产成本低的颗粒增强铝基复合材料在汽车部件上应用已成为新趋势，但外加颗粒增强体存在颗粒与基体界面结合弱，韧性差等问题；原位生成颗粒增强铝合金近年来成为热点，尤其是原位生成纳米颗粒强化铝合金具有强韧性好，抗疲劳能力强等特点，是理想的轻量化材料，其中纳米颗粒在基体中分布的均匀性是影响其性能发挥的关键。因此，本发明提出汽车发动机减震部件用AlSi9Cu3铝合金的原位纳米颗粒强化，并研发渐进式高致密压铸技术，借助压铸件的快速凝固结晶使纳米颗粒在基体均匀分布，充分发挥纳米增强体的强化作用；同时渐进式高致密压铸技术避免了传统突变式压铸速率导致铸件中驻留大量气孔，无法有效热处理的问题，显著提高其压铸件的力学性能。
对比现有技术文献发现，申请号为CN201611179327.5，名称为一种微合金铝基复合材料的轧制工艺的中国发明专利，公布了原位颗粒增强AlSi9Cu3合金及其余热直接轧制工艺，而本发明公布的是一种高性能原位纳米颗粒强化AlSi9Cu3合金及其渐进式高致密压铸技术。申请号为CN200610118386.1，名称为铝合金汽车发动机支架的挤压铸造方法的中国发明专利，所公布的发动机支架生产技术为挤压铸造，且所采用的合金也非AlSi9Cu3压铸铝合金。申请号为CN201611213315.X，名称为一种减震器支承座的生产工艺的中国发明专利，公布了严格控制压铸过程中保压的压力和时间，并将旋铆面上成 型不够致密的一段去掉，增加支承座抗疲劳性能的方法，而本专利则是通过原位纳米强化和高致密压铸技术提高减震部件的强塑性和抗疲劳性能。申请号为FR2969176A1，名称为Manufacturing part e.g.cylindrical casing of motor vehicle,comprises molding aluminum-silicon-copper alloy in mold,removing molded part,placing molded part in heat treatment furnace,and quenching molded part at a given temperature的法国发明专利，公布了采用常规铸造的方法生产AlSi9Cu3汽车部件的工艺，而本发明则是解决采用高效的压铸工艺所生产AlSi9Cu3减震部件强塑性、抗疲劳性能偏低的问题。申请号为DE102008039976A1，名称为Heat-treated hot isostatic pressing of light-metal cast components,comprises treating a body made of light metal cast alloys such as aluminum cast alloys and magnesium cast alloys的德国发明专利，公布了采用热等静压提高AlSi9Cu3等轻合金零部件性能的方法，而本专利的技术则是通过渐进式压铸获得高致密的高性能AlSi9Cu3发动机减震部件。
发明内容
本发明的目的就在于针对现有汽车发动机减震部件用AlSi9Cu3压铸铝合金强塑性、抗疲劳性能偏低，尤其是不能满足高性能发动机部件对其高强度、抗疲劳、抗冲击技术需求的不足，通过合金成分调控和原位纳米强化，并结合非线性高压压铸，在提高合金析出相的含量、圆顿化和细化同时，实现晶内和晶界的原位纳米陶瓷增强体强化，显著提高压铸制品的强塑性、抗疲劳性和阻尼性能。
采用本发明技术生产的汽车发动机用减震支架和壳体的抗拉强度可达352MPa，屈服强度达到285MPa，延伸率可达10.6％。最终产品经专用台架进行耐久性试验，最少循环次数达到了100万次，远高于客户要求的50万次，达到了德国大众(减震支架)DIN EN1706-1998标准和日本马自达(减震壳体)MES MM 621-ADC12标准，同时也超过了采用效率较低、成本相对高的低压铸造(低压铸造+固溶+时效热处理后)生产的减震支架性能(抗拉强度300MPa，屈服强度210MPa，延伸率7.5％)。
本发明的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金及其高致密压铸方法，通过合金成分调控和原位纳米强化，并结合优化的非线性高压压铸获得晶内和晶界包含大量且分散均匀的纳米ZrB 2陶瓷增强体，晶内包含纳米Al 3Er析出相，包括共晶Si相，Mg 2Si相，Al 2Cu相和含Fe相在内的合金析出相细小、圆顿的压铸件。借助纳米增强体和纳米析出相的弥散强化、界面阻尼效应以及低固溶度的Er元素在合金熔体产生的Al 3Er相的晶粒细化作用，显著提高合金构件的强塑性、抗疲劳和阻尼性能；与此 同时，和常规AlSi9Cu3合金相比Mg、Zn和Fe元素含量的提高，以及Mn和Ni元素引入，在保障良好压铸性能、提高合金强化相含量的同时，使Al-Fe相等合金强化相有效细化和圆顿化；从而，使本发明合金所生产的构件表现出高强塑性、高抗疲劳性和良好阻尼性能的特点。
本发明的制备方法包括以下步骤：
(1)合金熔炼：将AlSi9Cu3合金熔化至750-780℃并保温10min。所述的AlSi9Cu3合金为商用合金，其具体化学成分的元素质量百分比为：Si 8.0～11.0，Cu 2.0～3.5，Zn 1.0～1.5，Mg 0.3～0.5，Fe≤0.8，Mn 0.1～0.5，余量为Al。
(2)原位合成纳米ZrB 2陶瓷增强体：将Al-Zr和Al-B中间合金加入步骤(1)熔炼并保温的熔体中并迅速升温至840-860℃，同时采用石墨搅拌转子搅动熔体以促进合金的充分混合，保温时间为10-15min，使合金中的Zr和B元素在自由能降低的驱动力下原位反应合成纳米ZrB 2陶瓷增强体，然后降温至730-750℃并保温。使得步骤(2)合金中锆硼元素的质量百分比达到Zr：3.0-5.0，B：0.5-1.0。
(3)引入Er和Ni元素，调整合金中Fe和Mn元素的含量并精炼除气：将Al-Er、Al-Fe和Al-Mn中间合金以及纯Ni加入步骤(2)所获得的复合熔体中，并采用石墨搅拌转子搅动以促进合金的充分混合，保温搅拌时间为10-15min；然后将粒度小于500μm的粉末状复合精炼剂用惰性气体通过石墨转子的中空通道吹入熔体中，对熔体进行精炼除气，以去除合金高温熔炼和反应过程中产生的夹渣和熔体中溶入的氢，精炼温度为730-750℃，精炼保温时间为25-30min。最终使步骤(3)合金中铒镍铁元素含量达到Er：0.1-0.15，Fe：1.0～1.5，Mn：0.5～1.0，Ni 0.5～1.0。
(4)调整Mg，Zn元素的含量：将步骤(3)获得的熔体降温至660-700℃并保温，然后将纯Mg和纯Zn采用钟罩压入精炼除气后的熔体中，启动石墨搅拌转子，并慢速搅拌，保温搅拌时间>15min，以使Mg，Zn溶入合金并避免熔体吸气，且使步骤(4)合金中镁锌元素含量达到Mg：0.5～1.0，Zn：1.5～2.5。
(5)非线性高压压铸：将步骤(4)获得的复合熔体置入压铸机的保温包中，采用优化的非线性压铸工艺进行压铸获得纳米复合强化压铸件，其中压射速度为从小到大的抛物线式压射、以实现前期缓慢充型2.5-3m/s，终了瞬间高速充型的非线性充型(最大压射速度达到40-50m/s，压铸压力达到100-150MPa)。
(6)时效处理：将步骤(5)获得的压铸件进行时效处理(自然时效或人工时效)，以获得高强抗疲劳且阻尼性能好的原位纳米强化铝合金压铸件。
所述的Al-Zr、Al-B、Al-Er、Al-Fe和Al-Mn中间合金，优选合金化元素含量高的中间合金，如Al-10Zr、Al-10B、Al-20Er、Al-20Fe和Al-10Mn。
所述的原位合成纳米ZrB 2陶瓷增强体，是指利用该多元合金体系中ZrB 2的吉布斯自由能低，且Zr在Al中具有低溶解度和低热扩散系数的热力学-动力学特性，在合金中引入Zr、B元素后，在熔体中原位合成纳米级的ZrB 2陶瓷颗粒，其尺寸为20-80nm，含量为合金质量的2-6wt.％，合成温度为840-860℃。从而在合金熔体凝固过程中：一方面，原位纳米ZrB 2陶瓷颗粒可作为异质形核核心提高合金的形核率，细化晶粒，并最终包含分散于合金晶粒内部，显著提高合金的强度、抗疲劳性能；另一方面，未成为形核核心的纳米ZrB 2陶瓷颗粒会在晶粒长大的过程中分散于晶界，可有效钉扎晶界并阻碍晶界的迁移，提高合金强度的同时、最大化发挥界面阻尼作用，提高合金的阻尼性能。
所述的引入Er和Ni元素，调整合金中Fe和Mn元素的含量并精炼除气，是指在合金中引入的0.1-0.15wt.％的Er，一方面借助Er在铝溶体中低的溶解度(0.1wt.％)，在合金熔体中析出Al 3Er异质形核核心提高铝的形核率，细化合金晶粒，另一方面固溶于合金中Er元素，会在合金时效过程中在晶内析出细小且与铝基体晶格匹配良好的L1 2型纳米Al 3Er析出相，显著提高合金压铸件的时效强度和抗疲劳性能；在合金中增加Fe元素的含量的目的是提高合金中Fe析出相含量，提高合金强度的同时，进一步提高合金的抗粘模性能，避免合金析出相含量提高、膨胀系降低所导致的脱模难和粘模问题，引入Ni元素并提高Mn元素含量的目的是通过Ni、Mn与合金中针片状的β-Fe相转变成块状或汉字状的α-Al(Mn,Fe)Si和α-Al(Ni,Fe)Si相，避免Fe含量的提高产生大量的针状β-Fe相降低合金的塑韧性。
所述的调整Mg，Zn元素的含量，是进一步提高合金中析出相的含量，以提高合金强度，抗疲劳性能，并借助增加的相界提高合金的阻尼性能。
所述的非线性高压压铸工艺，是指采用压铸缸体速度可编程控制的新型压铸机，并结合优化其获得的非线性高压压铸工艺，以从避免熔体充型过程中的紊流和卷气、利于型腔中气体的排出并在充满型腔的瞬时高速高压下促进纳米增强体的浸润和分散，以获得组织缺陷少、性能优良的压铸产品。其中压射速度为从小到大的抛物线式压射、以实现前期缓慢充型2.5-3m/s，终了瞬间高速充型的非线性充型(最大压射速度达到40-50m/s，压铸压力达到100-150MPa)。
所述的高温时效热处理，是得益于渐进式压铸件气孔含量低的优势，可提高工件的时效热处理温度以促进强化相的有效析出和硅相的圆钝化，所述的高温时效热处理温度的范围为200℃-350℃。
附图说明
图1(a)为常规AlSi9Cu3压铸件金相组织图，(b)为本发明制备的高强抗疲劳且阻尼性能好的原位纳米强化铝合金减震支架压铸件金相组织图，从两金相组织图可以看出，采用本专利技术所制备的压铸件中针状析出相消失，转化为颗粒状或短片状的圆顿析出相，提高了析出相的弥散程度，利于工件强塑性和疲劳性能的提高。
图2为本发明制备的高强抗疲劳且阻尼性能好的原位纳米强化铝合金减震支架压铸件TEM组织图，从图中可以看出，采用本专利所制备的压铸件的晶内和晶界存在的原位纳米ZrB 2陶瓷增强相和更加细小的Al 3Er均匀纳米析出相，利于工件强塑性、抗疲劳性能和阻尼性能的综合提高。
具体实施方式
以下结合附图对本发明实施方案进一步描述：以下实施例在以本发明技术方案为前提下进行实施，给出了详细的实施方式和具体的操作过程，但本发明的保护范围不限于下述的实施例。
实施例1
以Al-10Zr、Al-10B、Al-20Er、Al-20Fe、Al-10Mn中间合金和纯Ni、纯Mg、纯Zn，以及AlSi9Cu3为原料，采用优化的非线性高压压铸技术制备汽车发动机用减震支架。
将熔融的500Kg商用AlSi9Cu3合金(760℃)转入中间保温炉中，然后将Al-10Zr和Al-10B中间合金加入保温炉中并升温至850℃，同时采用石墨搅拌转子搅动熔体以促进合金的充分混合，保温时间为15min，然后将合金降温至750℃并保温；将Al-20Er、Al-20Fe和Al-10Mn以及纯Ni加入熔体中，搅拌保温15min后将粒径小于500μm的粉末状复合精炼剂用惰性气体通过石墨转子的中空通道吹入熔体中，对熔体进行精炼除气，以去除合金高温熔炼和反应过程中产生的夹渣和熔体中溶入的氢，精炼时间为30min，温度保持在750℃，精炼除气结束后降温至680℃并将纯Mg和纯Zn用钟罩压入精炼除气后的熔体中，启动石墨搅拌转子，并慢速搅拌，保温搅拌时间18min，使合金最终成分达到Si 9.5，Cu 3，Zr 3.5，B 0.75，Zn 1.5，Mg 0.8，Fe 1.3，Mn 1.0，Ni 0.7，Er 0.12，余量为Al，最后将获得的复合熔体以优化的非线性高压压铸工艺制备减震支架，其中前期为3m/s缓慢充型，以实现平流充型并利于模具型腔中气体的顺利排出，待型腔充满(冒口未充满)的瞬间， 提高压射速度至40m/s，并保持压力至100MPa，保压时间为15s，获得压铸减震支架。
将切除浇冒口和飞边的压铸毛坯，放入热处理炉中进行人工时效，时效温度的300℃，时效时间为8小时。
取样分析表明，减震支架的硬度大于97HBS，抗拉强度达到了352MPa，屈服强度达到了285MPa，延伸率为10.6％，在7.6kN载荷下拉压疲劳试验寿命大于2×10 6次，最终产品经专用台架进行耐久性试验，最少循环次数达到了100万次，远高于客户要求50万次。产品达到德国大众(减震支架)DIN EN1706-1998标准和日本马自达(减震壳体)MES MM621-ADC12标准。如图1b所示为采用本实施例工艺所制备的减震支架的金相组织图，从图中可以看出相比常规AlSi9Cu3压铸件，本专利所制备的压铸件中的针状析出相消失，转化为颗粒状或短片状的圆顿析出相，提高了析出相的弥散程度，利于工件强塑性和疲劳性能的提高。图2为本实施例工艺所制备减震支架压铸件TEM组织图，从图中可以看出，采用本专利所制备的压铸件的晶内和晶界存在大量的原位纳米ZrB 2陶瓷增强相和更加细小均匀纳米Al 3Er纳米析出相，利于工件强塑性、抗疲劳性能和阻尼性能的综合提高。
实施例2
以Al-10Zr、Al-5B、Al-10Er、Al-10Fe、Al-10Mn中间合金和纯Ni、纯Mg、纯Zn，以及AlSi9Cu3为原料，采用优化的非线性高压压铸技术制备汽车发动机用减震壳体(壳体结构复杂充型和排出气体难度高，通常降低Mg含量，提高压铸压力，提高压铸件性能和成品率)。
将熔融的500Kg商用AlSi9Cu3合金(750℃)转入中间保温炉中，然后将Al-10Zr和Al-5B中间合金加入保温炉中并升温至840℃，同时采用石墨搅拌转子搅动熔体以促进合金的充分混合，保温时间为10min，然后将合金降温至740℃并保温；将Al-10Er、Al-10Fe和Al-10Mn以及纯Ni加入熔体中，搅拌保温10min后将粒径小于500μm的粉末状复合精炼剂用惰性气体通过石墨转子的中空通道吹入熔体中，对熔体进行精炼除气，以去除合金高温熔炼和反应过程中产生的夹渣和熔体中溶入的氢，精炼时间为25min，温度保持在740℃，精炼除气结束后降温至660℃并将纯Mg和纯Zn用钟罩压入精炼除气后的熔体中，启动石墨搅拌转子，并慢速搅拌，保温搅拌时间20min，使合金最终成分达到Si 11，Cu 3.5，Zr 5.0，B 1.0，Zn 2.0，Mg 0.5，Fe 1.5，Mn 1.0，Ni 0.5，Er 0.15，余量为Al，最后将获得的复合熔体以优化的非线性高压压铸工艺制备减震壳体，其中前期为5m/s缓慢充型，以实现平流充型并利于模具型腔中气体的顺利排出，待型腔充满(冒口未充满)的瞬间，提高压射速度至50m/s，并在保持压力至150MPa，时间为15s，获得压铸减震壳体。
将切除浇冒口和飞边的压铸毛坯，放入热处理炉中进行人工时效，时效温度的250℃，时效时间为10小时。
取样分析表明，减震支架的硬度大于92HBS，抗拉强度达到了315MPa，屈服强度达到了243MPa，延伸率为8.9％，在7.6kN载荷下拉压疲劳试验寿命大于1.5×10 6次，最终产品经专用台架进行耐久性试验，最少循环次数达到了100万次，远高于客户要求50万次。
实施例3
以Al-10Zr、Al-5B、Al-20Er、Al-20Fe、Al-5Mn中间合金和纯Ni、纯Mg、纯Zn，以及AlSi9Cu3为原料，采用优化的非线性高压压铸技术制备汽车发动机用油泵壳体。
将熔融的500Kg商用AlSi9Cu3合金(780℃)转入中间保温炉中，然后将Al-10Zr和Al-5B中间合金加入保温炉中并升温至860℃，同时采用石墨搅拌转子搅动熔体以促进合金的充分混合，保温时间为15min，然后将合金降温至750℃并保温；将Al-20Er、Al-20Fe和Al-50Mn以及纯Ni加入熔体中，搅拌保温10min后将超细的粉末状精炼剂用惰性气体通过石墨转子的中空通道吹入熔体中，对熔体进行精炼除气，以去除合金高温熔炼和反应过程中产生的夹渣和熔体中溶入的氢，精炼时间为30min，温度保持在750℃，精炼除气结束后降温至680℃并将纯Mg和纯Zn用钟罩压入精炼除气后的熔体中，启动石墨搅拌转子，并慢速搅拌，保温搅拌时间20min，使合金最终成分达到Si 11，Cu 2.5，Zr 5.0，B 1.0，Zn 2.5，Mg 1.0，Fe 1.5，Mn 1.0，Ni 1.0，Er 0.1，余量为Al，最后将获得的复合熔体以优化的非线性高压压铸工艺制备油泵壳体，其中前期为4m/s缓慢充型，以实现平流充型并利于模具型腔中气体的顺利排出，待型腔充满(冒口未充满)的瞬间，提高压射速度至50m/s，并在保持压力至130MPa，时间为15s，获得压铸油泵壳体。
将切除浇冒口和飞边的压铸毛坯，放入热处理炉中进行人工时效，时效温度的220℃，时效时间为15小时。
取样分析表明，减震支架的硬度大于93HBS，抗拉强度达到了330MPa，屈服强度达到了250MPa，延伸率为7.8％，在7.6kN载荷下拉压疲劳试验寿命大于1.2×10 6次，最终产品经专用台架进行耐久性试验，最少循环次数达到了100万次，远高于客户要求50万次。
对比实施方式
对比实施例1
以AlSi9Cu3合金为原料，采用优化的非线性高压压铸技术制备汽车发动机用减震支架。
将熔融的500Kg商用AlSi9Cu3合金(700℃)采用优化的非线性高压压铸技术制备汽 车发动机用减震支架，并对切除浇冒口和飞边的压铸毛坯进行人工时效，时效温度的300℃，时效时间为8小时。
取样分析表明，减震支架的硬度大于82HBS，抗拉强度达到了285MPa，屈服强度达到了193MPa，延伸率为6.4％，在7.6kN载荷下拉压疲劳试验寿命大于1×10 6次。
对比实施例2
以Al-10Zr、Al-10B、Al-20Er、Al-20Fe、Al-10Mn中间合金和纯Ni、纯Mg、纯Zn，以及AlSi9Cu3为原料，采用常规压铸技术制备汽车发动机用减震支架。
原位合成纳米ZrB 2增强体及合金成分调控与实施例1相同，将获得温度为680℃，成分为Si 9.5，Cu 3，Zr 3.5，B 0.75，Zn 1.5，Mg 0.8，Fe 1.3，Mn 1.0，Ni 0.7，Er 0.12，余量为Al的合金熔体，采用常规压铸工艺获得压铸减震支架。
采用实施例1相同的时效工艺对压铸件进行时效处理。
取样分析表明，减震支架的硬度大于93HBS，抗拉强度达到了335MPa，屈服强度达到了263MPa，延伸率为9.2％，在7.6kN载荷下拉压疲劳试验寿命大于1.8×10 6次。

Claims (7)

  1. 一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金，其特征在于：通过合金成分调控和原位纳米强化，并结合优化的非线性高压压铸获得晶内和晶界包含大量且分散均匀的纳米ZrB 2陶瓷增强体，晶内包含纳米Al 3Er析出相，以及包括共晶Si相，Mg 2Si相，Al 2Cu相和含Fe相在内的合金析出相细小、圆顿的压铸件；其具体化学成分的元素质量百分比为：Si 8.0～11.0，Cu 2.0～3.5，Zr 3.0-5.0，B 0.5-1.0，Zn 1.5～2.5，Mg 0.5～1.0，Fe 1.0～1.5，Mn 0.5～1.0，Ni 0.5～1.0，Er 0.1-0.15，余量为Al；借助纳米增强体和纳米析出相的弥散强化、界面阻尼效应以及低固溶度的Er元素在合金熔体产生的Al 3Er相晶粒细化作用，显著提高合金构件的强塑性、抗疲劳和阻尼性能；与此同时，Mg、Zn和Fe元素含量的提高，以及Mn和Ni元素引入，在保障良好压铸性能、提高合金强化相含量的同时，使Al-Fe相等合金强化相有效细化和圆顿化；从而，协同提高强塑性、抗疲劳性和阻尼性能。
  2. 如权利要求1所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，具体步骤如下：
    (1)合金熔炼：将AlSi9Cu3合金熔化至750-780℃并保温；所述的AlSi9Cu3合金为商用合金，其具体化学成分的元素质量百分比为：Si 8.0～11.0，Cu 2.0～3.5，Zn 1.0～1.5，Mg 0.3～0.5，Fe≤0.8，Mn 0.1～0.5，余量为Al；
    (2)原位合成纳米ZrB 2纳米陶瓷增强体：将Al-Zr和Al-B中间合金加入步骤(1)熔炼并保温的熔体中并迅速升温至840-860℃，同时采用石墨搅拌转子搅动熔体以促进合金的充分混合，保温时间为10-15min，使合金中的Zr和B元素在自由能降低的驱动力下原位反应合成纳米ZrB 2陶瓷增强体，然后降温至730-750℃并保温，使得步骤(2)合金中锆硼元素的质量百分比达到Zr：3.0-5.0，B：0.5-1.0；
    (3)引入Er和Ni元素，调整合金中Fe和Mn元素的含量并精炼除气：将Al-Er、Al-Fe和Al-Mn中间合金以及纯Ni加入步骤(2)所获得的复合熔体中，并采用石墨搅拌转子搅动以促进合金的充分混合，保温搅拌时间为10-15min；然后将粒度小于500μm的粉末状复合精炼剂用惰性气体通过石墨转子的中空通道吹入熔体中，对熔体进行精炼除气，以去除合金高温熔炼和反应过程中产生的夹渣和熔体中溶入的氢，精炼温度为730-750℃，精炼保温时间为25-30min，最终使步骤(3)合金中铒镍铁元素含量达到Er：0.1-0.15，Fe：1.0～1.5，Mn：0.5～1.0，Ni 0.5～1.0。
    (4)调整Mg，Zn元素的含量：将步骤(3)获得的熔体降温至660-700℃并保温，然后将纯Mg和纯Zn采用钟罩压入精炼除气后的熔体中，启动石墨搅拌转子，并慢速搅拌，保温搅拌时间>15min，以使Mg，Zn溶入合金并避免熔体吸气，且使步骤(4)合金中镁锌元素含量达到Mg：0.5～1.0，Zn：1.5～2.5；
    (5)非线性高压压铸：将步骤(4)获得的复合熔体置入压铸机的保温包中，采用优化的非线性压铸工艺进行压铸，获得纳米复合强化压铸件，其中压射速度为从小到大的抛物线式压射；
    (6)时效处理：将步骤(5)获得的压铸件进行时效处理，以获得高强抗疲劳且阻尼性能好的原位纳米强化铝合金压铸件。
  3. 如权利要求2所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，所述的Al-Zr、Al-B、Al-Er、Al-Fe和Al-Mn中间合金，选择合金化元素含量高的中间合金，具体为Al-10Zr、Al-10B、Al-20Er、Al-20Fe和Al-10Mn。
  4. 如权利要求2所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，所述的原位合成纳米ZrB 2纳米陶瓷增强体，是指利用该多元合金体系中ZrB 2的吉布斯自由能低，且Zr在Al中具有低溶解度和低热扩散系数的热力学-动力学特性，在合金中引入Zr、B元素后，在熔体中原位合成纳米级的ZrB 2陶瓷颗粒，其尺寸为20-80nm，含量为合金质量的2-6wt.％，合成温度为840-860℃；从而在合金熔体凝固过程中：一方面，原位纳米ZrB 2陶瓷颗粒可作为异质形核核心提高合金的形核率，细化晶粒，并最终包含分散于合金晶粒内部，显著提高合金的强度、抗疲劳性能；另一方面，未成为形核核心的纳米ZrB 2陶瓷颗粒会在晶粒长大的过程中分散于晶界，可有效钉扎晶界并阻碍晶界的迁移，提高合金强度的同时、最大化发挥界面阻尼作用，提高合金的阻尼性能。
  5. 如权利要求2所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，所述的引入Er和Ni元素，调整合金中Fe和Mn元素的含量并精炼除气，是指在合金中引入的0.1-0.15wt.％的Er，一方面借助Er在铝溶体中低的溶解度，在合金熔体中析出Al 3Er异质形核核心提高铝的形核率，细化合金，另一方面固溶于合金中Er元素，会在合金时效时在晶内析出细小且与铝基体晶格匹配良好的L1 2型纳米Al 3Er析出相，尺寸为2-10nm，显著提高合金压铸件的时效强度和抗疲劳性能。
  6. 如权利要求2所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，在合金中增加Fe元素的含量，用于提高合金中Fe析出 相含量，提高合金强度的同时，进一步提高合金的抗粘模性能，避免合金析出相含量增高、膨胀系降低所导致脱模难和粘模问题；引入Ni元素并提高Mn元素含量的目的是通过Ni、Mn与合金中针片状的β-Fe相转变成块状或汉字状的α-Al(Mn,Fe)Si和α-Al(Ni,Fe)Si相，避免Fe含量的提高产生大量的针状β-Fe相降低合金的塑韧性；所述的调整Mg，Zn元素的含量，是进一步提高合金中析出相的含量，以提高合金强度，抗疲劳性能，并借助增加的相界提高合金的阻尼性能。
  7. 如权利要求2所述的一种汽车发动机减震部件用高强抗疲劳原位纳米强化铝合金的高致密压铸方法，其特征在于，所述的非线性高压压铸工艺，是指采用压铸缸体速度可编程控制的压铸机，并优化其获得的非线性高压压铸工艺，以从避免熔体充型过程中的紊流和卷气、利于型腔中气体的排出并在充满型腔的瞬时高速高压下促进纳米增强体的浸润和分散，以获得组织缺陷少、性能优良的压铸产品；所述压射速度为从小到大的抛物线式压射、以实现前期缓慢充型2.5-3m/s，终了瞬间高速充型的非线性充型，最大压射速度达到40-50m/s，压铸压力达到100-150MPa。
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CN114959372A (zh) * 2022-03-08 2022-08-30 山东金马汽车装备科技有限公司 一种铝基复合材料轮毂及其制造方法
CN114959372B (zh) * 2022-03-08 2023-06-27 山东金马汽车装备科技有限公司 一种铝基复合材料轮毂及其制造方法

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